We experimentally demonstrate the formation and stable propagation of various types of discrete temporal solitons in an optical fiber system. Pulses interacting with a time-periodic potential and defocusing nonlinearity are shown to form gap solitons and nonlinear truncated Bloch waves. Multi-pulse solitons with defects, as well as novel structures composed of a strong soliton riding on a weaker truncated nonlinear Bloch wave are shown to propagate over up to eleven coupling lengths. The nonlinear dynamics of all pulse structures is monitored over the full propagation distance which provides detailed insight into the soliton dynamics.

We define a new diffusive matrix model converging toward the $\beta$-Dyson Brownian motion for all $\beta \in [0,2]$ that provides an explicit construction of beta ensembles of random matrices that is invariant under the orthogonal or unitary group. For small values of $\beta$, our process allows one to interpolate smoothly between the Gaussian distribution and the Wigner semicircle. The interpolating limit distributions form a one parameter family that can be explicitly computed. This also allows us to compute the finite-size corrections to the semicircle.

The Adam-Gibbs relation between relaxation times and the configurational entropy has been tested extensively for glass formers using experimental data and computer simulation results. Although the form of the relation contains no dependence on the spatial dimensionality in the original formulation, subsequent derivations of the Adam-Gibbs relation allow for such a possibility. We test the Adam-Gibbs relation in two, three, and four spatial dimensions using computer simulations of model glass formers. We find that the relation is valid in three and four dimensions. But in two dimensions, the relation does not hold, and interestingly, no single alternate relation describes the results for the different model systems we study.

We present the observation of glasslike dynamic correlations of mobile mercury ions in the ionic conductor ${\mathrm{Cu}}_2{\mathrm{HgI}}_4$, detected in both NMR and nonlinear conductivity experiments. The results show that dynamic cooperativity appears in systems seemingly unrelated to glassy and soft arrested materials. A simple kinetic two-component model is proposed, which seems to provide a good description of the cooperative ionic dynamics.

We report a frequency coding limit cycle and anomalous capacitance in the Kondo insulator ${\mathrm{SmB}}_6$ at low temperatures where the insulating gap becomes fully opened. The limit cycle appears to be associated with local activity and autocatalytic temporal pattern formation, as occurs in biological systems. The measured anomalous capacitance may indicate surface and bulk separation, suggesting the formation of a surface conducting state. The biological analogy suggests lossless information transport and complex information coding, and the surface state with a superconductor would provide a possible venue for quantum computing resources without decoherence.

We show that in a perpendicularly magnetized $\mathrm{Pt}/\mathrm{Co}$ bilayer the spin-Hall effect (SHE) in Pt can produce a spin torque strong enough to efficiently rotate and switch the Co magnetization. We calculate the phase diagram of switching driven by this torque, finding quantitative agreement with experiments. When optimized, the SHE torque can enable memory and logic devices with similar critical currents and improved reliability compared to conventional spin-torque switching. We suggest that the SHE torque also affects current-driven magnetic domain wall motion in $\mathrm{Pt}/\mathrm{\text{ferromagnet}}$ bilayers.

In a semiconductor heterostructure, the Coulomb interaction is responsible for the electric current drag between two 2D electron gases across an electron impenetrable insulator. For two metallic layers separated by a ferromagnetic insulator (FI) layer, the electric current drag can be mediated by a nonequilibrium magnon current of the FI. We determine the drag current by using the semiclassical Boltzmann approach with proper boundary conditions of electrons and magnons at the metal–FI interface.

The effects of phosphorus doping on the structural and superconducting phase transitions of ${\mathrm{BaNi}}_2({\mathrm{As}}_{1\mathrm{\text{−}}x}{\mathrm{P}}_x{)}_2$ were studied. The specific heat, resistivity, and magnetic susceptibility were measured. The results revealed an abrupt increase in the superconducting transition temperature ($T_c$) from 0.6 K in the triclinic phase (space group $P\overline{1}$) with less phosphorus ($x\le 0.067$) to 3.3 K in the tetragonal phase (space group $I4/mmm$) with more phosphorus ($x\ge 0.067$). Our data analysis suggests that a doping-induced softening related to an in-plane Ni and $\mathrm{As}(\mathrm{P})$ phonon mode is responsible for the enhanced superconductivity in the tetragonal phase.

We show that the electronic structures of the title compounds predicted by density functional theory are well described by tight binding models. We determine the frustration ratio, $J^{\prime }/J$, of the Heisenberg model on the anisotropic triangular lattice, which describes the spin degrees of freedom in the Mott insulating phase for a range of $\mathrm{Pd}(\mathrm{dmit}{)}_2$ salts. All of the antiferromagnetic materials studied have $J^{\prime }/J\lesssim 0.5$ or $J^{\prime }/J\gtrsim 0.9$, and all salts with $0.5\lesssim J^{\prime }/J\lesssim 0.9$ are known, experimentally, to be charge ordered valence-bond solids or spin liquids.

This work revisits the physics giving rise to the carbon nanotube phonon bands in the midinfrared. Our measurements of doped and undoped samples of single-walled carbon nanotubes in Fourier transform infrared spectroscopy show that the phonon bands exhibit an asymmetric line shape and that their effective cross section is enhanced upon doping. We relate these observations to electron-phonon coupling or, more specifically, to a Fano resonance phenomenon. We note that the dopant-induced intraband (not interband) continuum couples strongly to the phonon modes, and that defects created on the sidewall are scattering centers that increase the spectral amplitude of the resonance.

Complementary diffuse and inelastic synchrotron x-ray scattering measurements of lead zirconate-titanate single crystals with composition near the morphotropic phase boundary ($x=0.475$) are reported. In the temperature range $293\mathrm{K}<T<400\mathrm{K}$ a highly anisotropic quasielastic diffuse scattering is observed. Above 400 K this scattering disappears. Its main features can be reproduced by the model of inhomogeneous lattice deformations caused by inclusions of a tetragonal phase into a rhombohedral or monoclinic phase. This observation supports the idea that PZT at its morphotropic phase boundary is essentially structurally inhomogeneous.

Using a network representation for real soil samples and mathematical models for microbial spread, we show that the structural heterogeneity of the soil habitat may have a very significant influence on the size of microbial invasions of the soil pore space. In particular, neglecting the soil structural heterogeneity may lead to a substantial underestimation of microbial invasion. Such effects are explained in terms of a crucial interplay between heterogeneity in microbial spread and heterogeneity in the topology of soil networks. The main influence of network topology on invasion is linked to the existence of long channels in soil networks that may act as bridges for transmission of microorganisms between distant parts of soil.

We show that the smooth geometry of a hyperbolic 3-manifold emerges from a classical spin system defined on a 2D discrete lattice, and moreover, show that the process of this “dimensional oxidation” is equivalent with the dimensional reduction of a supersymmetric gauge theory from 4D to 3D. More concretely, we propose an equality between (1) the 4D superconformal index of a 4D $\mathcal{N}=1$ superconformal quiver gauge theory described by a bipartite graph on $T^2$ and (2) the partition function of a classical integrable spin chain on $T^2$. The 2D spin system is lifted to a hyperbolic 3-manifold after the dimensional reduction and using the Higgs mechanism in the 4D gauge theory.

While bulk properties of stable nuclei are successfully reproduced by mean-field theories employing effective interactions, the dependence of the centroid energy of the electric giant dipole resonance on the nucleon number $A$ is not. This problem is cured by considering many-particle correlations beyond mean-field theory, which we do within the quasiparticle time blocking approximation. The electric giant dipole resonances in ${}^{16}\mathrm{O}$, ${}^{40}\mathrm{Ca}$, and ${}^{208}\mathrm{Pb}$ are calculated using two new Skyrme interactions.

We investigate experimentally resonant radiation processes driven by slow solitons in a dispersion-engineered photonic crystal waveguide in a regime virtually free of dissipative nonlinear processes (two-photon absorption and Raman scattering). Strong (30% energy conversion) Cherenkov-like radiation accompanied by the blue self-frequency shift of the soliton is observed close to the zero dispersion point, and is explained in terms of the soliton-radiation locking of the velocity.

We propose and implement a wide-field microscopy method to retrieve the real and imaginary part of a field emitted by coherent and resonant molecular scatterers. The technique is based on wave-front sensing and does not require the use of any reference beam. We exemplify its ability in wide-field coherent anti-Stokes Raman scattering imaging and retrieve the complex anti-Stokes field while spectrally scanning a molecular vibrational resonance. This approach gives access to the background-free Raman spectrum of the targeted molecular bond.

We present atomistic first principles results for the lattice thermal conductivity of GaN and compare them to those for GaP, GaAs, and GaSb. In GaN we find a large increase to the thermal conductivity with isotopic enrichment, $\sim 65\%$ at room temperature. We show that both the high thermal conductivity and its enhancement with isotopic enrichment in GaN arise from the weak coupling of heat-carrying acoustic phonons with optic phonons. This weak scattering results from stiff atomic bonds and the large Ga to N mass ratio, which give phonons high frequencies and also a pronounced energy gap between acoustic and optic phonons compared to other materials. Rigorous understanding of these features in GaN gives important insights into the interplay between intrinsic phonon-phonon scattering and isotopic scattering in a range of materials.

Crystal surfaces may undergo thermodynamical as well as kinetic, out-of-equilibrium instabilities. We consider the case of mound and pyramid formation, a common phenomenon in crystal growth and a long-standing problem in the field of pattern formation and coarsening dynamics. We are finally able to attack the problem analytically and get rigorous results. Three dynamical scenarios are possible: perpetual coarsening, interrupted coarsening, and no coarsening. In the perpetual coarsening scenario, mound size increases in time as $L\sim t^n$, where the coarsening exponent is $n=1/3$ when faceting occurs, otherwise $n=1/4$.

We investigate the location and nature of the para-ferro transition of interacting electrons in dispersionless bands using the example of the Hubbard model on the Tasaki lattice. This case can be analyzed as a geometric site-percolation problem where different configurations appear with nontrivial weights. We provide a complete exact solution for the one-dimensional case and develop a numerical algorithm for the two-dimensional case. In two dimensions the paramagnetic phase persists beyond the uncorrelated percolation point, and the grand-canonical transition is via a first-order jump to an unsaturated ferromagnetic phase.

With decreasing density $n_s$ the thermopower $S$ of a low-disorder two-dimensional electron system in silicon is found to exhibit a sharp increase by more than an order of magnitude tending to a divergence at a finite disorder-independent density $n_t$ consistent with the critical form $(-T/S)\propto (n_s-n_t{)}^x$ with $x=1.0\pm 0.1$ ($T$ is the temperature). Our results provide clear evidence for an interaction-induced transition to a new phase at low density in a strongly interacting 2D electron system.